Abstract: A polygon mirror is placed so that its rotation axis is positioned on a center line in a main scanning direction of an image forming area scanned by each light beam. Moreover, two light beam irradiating optical units are placed so that the light beams are incident on reflective surfaces of the polygon mirror from directions that cross the line and are point symmetrical to each other with respect to the rotation axis of the polygon mirror. Further, two f? lenses are placed so that their lens center positions are displaced in mutually opposite directions from the center line in the main scanning direction of the image forming area.

Abstract: In an image forming apparatus, a polygon mirror, a plurality of laser generators, a first sensor, and a second sensor are disposed at a frame formed with a resin. A laser beam outputted from the laser generator and deflected by a deflection surface is irradiated onto a photosensitive surface of a photosensitive drum to scan the photosensitive surface over a scan part. The first sensor is disposed at a first position to detect a laser beam deflected by the deflection surface. The second sensor is disposed at a second position to detect a laser beam deflected by the deflection surface. A storage unit stores correspondence information indicating shift of the scan part from a reference scan part in relation to time difference between detections of the laser beam by the first sensor and the laser beam by the second sensor. The correspondence information varies with temperature variation in the frame. A controller controls the laser generator to output a laser beam based on the shift of the scan part.

Abstract: In an image-forming device, a plurality of laser beams is irradiated onto the reflecting surface of a polygon mirror so as to be obliquely incident thereon. A plurality of mixture preventing elements is provided for preventing a laser beam from mixing in optical paths for another light beams.

Abstract: An optical scanner includes a scanning unit having a reflecting surface that reflects a laser beam and scans the laser beam in a primary scanning direction, a laser beam radiation unit that radiates laser beams to the reflecting surface from directions at predetermined angles to a reference plane, which is orthogonal to the reflecting surface and extending along the primary scanning direction, and optical members provided on optical paths of the laser beams after reflections. The laser beam radiation unit radiates the laser beams, in such a manner that, an angle on a plane orthogonal to the reference plane between a first and second optical paths is larger than an angle between the first and third optical paths, the second and third optical paths being adjacent to one side and other side of the first optical path, respectively. The optical member on the second optical path is nearer the reflecting surface than the third optical path.

Abstract: A device for holding a laser diode (LD) and a collimate lens. A laser unit includes an LD supporting section supporting the LD, and a lens supporting section supporting the lens positioned opposite to the LD. A connecting portion connects the lens supporting section to the LD supporting section. An adjustment section for adjusting a relative position between the LD and the lens is provided in association with the LD supporting section. The adjustment section allows the LD supporting section to be movable and position-fixable with respect to the lens supporting section as if the LD supporting section serves as a leverage about the connecting portion functioning as a fulcrum.

Abstract: An optical scanner includes a scanning unit having a reflecting surface that reflects a laser beam and scans the laser beam in a primary scanning direction, a laser beam radiation unit that radiates laser beams to the reflecting surface from directions at predetermined angles to a reference plane, which is orthogonal to the reflecting surface and extending along the primary scanning direction, and optical members provided on optical paths of the laser beams after reflections. The laser beam radiation unit radiates the laser beams, in such a manner that, an angle on a plane orthogonal to the reference plane between a first and second optical paths is larger than an angle between the first and third optical paths, the second and third optical paths being adjacent to one side and other side of the first optical path, respectively. The optical member on the second optical path is nearer the reflecting surface than the third optical path.

Abstract: A scanning unit for use in an image-forming device includes, for example, four light sources that emit light beams corresponding to yellow, magenta, cyan and black images. The light beams are scanned over the corresponding photosensitive drum with the use of a single polygon mirror and four optical reflection systems each including reflection mirrors. The curved orientation of the scan lines on the photosensitive drum can be equalized for all four light beams by regulating the number of reflection mirrors, that is, by setting the number of reflection mirrors to an even number or an odd number.

Abstract: A first holder plate that holds a first laser emitting portion and that has a first insertion hole formed therein, a second holder plate that holds a second laser emitting portion and that has a second insertion hole formed therein, and a base plate that supports a first collimating lens and a second collimating lens and that has a first screwing hole and a second screwing hole formed therein, are continuously formed by a bending process. A slit plate having two slits bored therein which are disposed in parallel and in a sub scanning direction is provided between a reflecting mirror and a cylindrical lens. The reflecting mirror combines the optical paths of two laser beams emitted from the two laser emitting portions such that the optical paths are matched in a main scanning direction. The cylindrical lens allows the two laser beams to converge in the sub scanning direction.

Abstract: A polygon mirror is placed so that its rotation axis is positioned on a center line in a main scanning direction of an image forming area scanned by each light beam. Moreover, two light beam irradiating optical units are placed so that the light beams are incident on reflective surfaces of the polygon mirror from directions that cross the line and are point symmetrical to each other with respect to the rotation axis of the polygon mirror. Further, two f? lenses are placed so that their lens center positions are displaced in mutually opposite directions from the center line in the main scanning direction of the image forming area.

Abstract: A polygon mirror including a plurality of reflection surfaces. Each reflection surface has a writing region and two non-writing regions. The writing region includes a first reflecting section and a second reflecting section positioned downstream of the first reflecting section in a rotating direction of the polygon mirror. One non-writing section is positioned at an upstream end of each reflecting surface, and the other non-writing region is positioned at a downstream end of each reflecting surface. The first reflecting section has a reflection factor higher than a second reflection factor of the second reflecting section. A foggy region appears in the first reflecting section.

Abstract: A laser-control circuit board is mounted in a scanner to extend substantially parallel to a base plate, a bottom cover, and a top cover of the scanner. A synchronization detection element is attached to the under surface of the laser-control circuit board. A light beam is emitted from a light source, deflected by a polygon mirror, and is guided below the laser-control circuit board by various optical elements including a condenser lens, thereby being finally detected by the synchronization detection element. A through-hole is formed through the laser-control circuit board to check whether the synchronization detection element is in alignment with the condenser lens and other optical elements below the laser-control circuit board.

Abstract: A scanning unit for use in an image-forming device includes, for example, four light sources that emit light beams corresponding to yellow, magenta, cyan and black images. The light beams are scanned over the corresponding photosensitive drum with the use of a single polygon mirror and four optical reflection systems each including reflection mirrors. The curved orientation of the scan lines on the photosensitive drum can be equalized for all four light beams by regulating the number of reflection mirrors, that is, by setting the number of reflection mirrors to an even number or an odd number.

Abstract: In an image-forming device, a plurality of laser beams is irradiated onto the reflecting surface of a polygon mirror so as to be obliquely incident thereon. A plurality of mixture preventing elements is provided for preventing a laser beam from mixing in optical paths for another light beams.

Abstract: An image-forming device includes: a housing; an endless belt; a plurality of process units; and a plurality of scanner units. Each scanner unit and each process unit are inclined obliquely to a vertical direction. At least a part of each process unit is inserted into and removed from the housing in an obliquely inclined direction.

Abstract: An image forming apparatus includes a main casing; a photosensitive member; a process cartridge that can be installed or removed with respect to the main casing along a removal path; a scanner unit located above the process cartridge when the process cartridge is installed in the main casing; a sheet accommodating portion located at a bottom portion of the main casing; a pick-up roller located above the sheet accommodating portion; and a feed path along which a sheet can be conveyed from the sheet accommodating portion to a discharge port.

Abstract: A laser beam scanner converges a laser beam by using a first f? lens and a second f? lens in a main-scanning direction and in a sub-scanning direction, respectively, onto a photosensitive medium, thereby forming a scanning line on the photosensitive medium along the main-scanning direction. Before scanning the photosensitive medium, the laser beam that has passed through and been converged by the first f? lens, but not passed through the second f? lens, is guided to a beam detector and converged by a cylinder lens in the sub-scanning direction so that the laser beam falls within a detection area of the beam detector. The beam detector determines a scan start time by detecting the laser beam.

Abstract: A laser printer for forming toner images on sheets includes a duct wall and a shutter. The duct wall extends between a process cartridge, which is filled with toner, and a thermal fixing unit, which generates heat to fix toner images onto the sheets. The duct wall defines a duct and is formed with openings at its side that faces the thermal fixing unit. A fan is provided for drawing hot air from the thermal fixing unit, through the openings in the duct wall and the duct itself, and out from the laser printer. The shutter moves in and out of contact with the process cartridge in association with opening and closing movement of a cover of the laser printer. When the shutter is in contact with the process cartridge, an exhaust chamber is formed that connects an ozone exhaust hole of the process cartridge with the duct. Another fan is provided for drawing the ozone generated by a charge unit of the process cartridge through the ozone exhaust hole, the exhaust chamber, and the duct.

Abstract: A polygon mirror including a plurality of reflection surfaces. Each reflection surface has a writing region and two non-writing regions. The writing region includes a first reflecting section and a second reflecting section positioned downstream of the first reflecting section in a rotating direction of the polygon mirror. One non-writing section is positioned at an upstream end of each reflecting surface, and the other non-writing region is positioned at a downstream end of each reflecting surface. The first reflecting section has a reflection factor higher than a second reflection factor of the second reflecting section. A foggy region appears in the first reflecting section.

Abstract: A laser beam reflected off a polygon mirror travels below a beam portion and is reflected off a reflection mirror. The laser beam reflected off the reflection mirror is emitted through an opening formed directly below the beam portion. The beam portion is provided above the opening through leg portions. With the structure, the rigidity on the periphery of the opening can be ensured. Supporting portions for supporting the reflection mirror are reinforced by reinforcing portions, so that the reflection mirror is prevented from being vibrated. In addition, the reflection mirror is supported such that the reflection mirror does not contact the beam portion. Even when the beam portion is vibrated, the vibration is not conveyed from the beam portion to the reflection mirror.

Abstract: A device for holding a laser diode (LD) and a collimate lens. A laser unit includes an LD supporting section supporting the LD, and a lens supporting section supporting the lens positioned opposite to the LD, A connecting portion connects the lens supporting section to the LD supporting section. An adjustment section for adjusting a relative position between the LD and the lens is provided in association with the LD supporting section. The adjustment section allows the LD supporting section to be movable and position-fixable with respect to the lens supporting section as if the LD supporting section serves as a leverage about the connecting portion functioning as a fulcrum.